Netherlands Stations Made RLR

The PSMSL generally recommends that only
Revised Local Reference (RLR) data be used for analysis of long-term
variations in sea level. However, there are a few records, most notably those
from the Netherlands, that have been suitable for time series analysis. These
records have not been classified as RLR in the past because they have been
reported relative to a national levelling system (Normaal Amsterdamsch Peil or
NAP), which is explained in greater detail in the
RLR page.
However, a recent re-levelling of NAP in 2005 introduced a small datum
shift for the tide gauge time series. In order to maintain utility of these
long records, we have reclassified most of the Netherlands records as RLR and
introduced different RLR factors for the periods before and after 2005. While
these records do not meet the strict definition of RLR and may still include
prior re-levelling adjustments, we believe this represents the best path
forward.